episode34

034 How Lateral Inhibition Enhances Visual Edges

In this video, Leslie explains all about lateral inhibition using two rectangles. Watch to learn how this process helps us see edges of objects more clearly. Enjoy!

Transcript of Today’s Episode

Welcome to another episode of Interactive Biology TV, where we’re making biology fun! My name is Leslie Samuel. In this episode, Episode 34, I’m going to talk about how lateral inhibition enhances visual edges. What am I talking about? Well, you’re going to see right now.

Here, we have 2 rectangles. One is darker and the other is lighter. It’s just a solid gray color over here, and a solid darker gray, almost black color, over here. What I’m going to do is I’m going to show you something that’s quite fascinating, at least it’s fascinating to me. It illustrates how visual processing can lead to some interesting things. To a certain extent, it shows that what you see is not always what’s there.

What am I talking about? Well, what I’m going to do is I’m going to take this gray rectangle over here and I’m basically going to move it towards the other one. We’re going to see what happens. Remember it’s a solid gray color, the same color that I have over here, it’s the same color that I have over here, and throughout the entire rectangle. Now let’s put them together and see if anything happens. So I’m just going to move the one on the right towards the one at the left. And now, hopefully you can see this, depending on the monitor that you’re using, you may or may not be able to see this, but I’m guessing you will be able to see it.

What you’re going to notice here is right here at the border, you’re going to see that here is just a little lighter than over here. So before, it looked like a solid gray object, and I really hope you see this, or else this is pointless, and over here now, we’re seeing that it’s darker here than it is over here. If you don’t see it, look closely at the monitor and see if you see a little bit of a lighter edge here.

Now, is that lighter edge there? No, it really isn’t. But there’s something that’s happening inside your eye that’s making it seem as if it’s lighter over here and a little darker over here, you might be able to see that also. So, lighter on this side, and darker on this side, just a little bit. What we’re going to do is look at why that’s the case.

The main idea, though, is that the brain is set up to enhance visual edges so that you can see the edges more clearly. I find this to be very fascinating because to me, it illustrates that maybe what we see might not actually be what is there. And I don’t know how much that extends into everyday life, but it’s an interesting concept nonetheless. Now, let’s look at the cells that we have in the retina.

We looked at this already. We said that here we have the rods and this would be a cone, we said that here we have a horizontal cell, and here we have ganglion cells, and we also have amacrine cells. This is just a review of an earlier episode. The cell that I’m most concerned with now in terms of this process is the horizontal cell. You can see here, we have a number of rods, and we have a cone, and this horizontal cell goes laterally, and it connects to multiple rods and even connects to some of the cones. This is where the processing that enhances those visual edges starts.

So it’s happening in the retina, this entire thing is in the retina. What happens is if it’s getting a lot of intense stimulation from a group of rods over here, that causes this horizontal cell to inhibit some of the other cells so you do not get as much stimulation from those receptors that are not stimulated as intensely as these over here. So we have a strong stimulation coming via these rods or these receptor cells, and that’s causing inhibition of some of the cells that are not being stimulated as much. This process is called lateral inhibition, and to me it’s a very fascinating concept, showing that strong activity over here can inhibit activity in another area.

That’s all I want to cover in this episode. That’s it for this video. If you have any questions or comments, go ahead and leave them below, and I’ll be happy to take a look at them, and maybe even answer the questions that you might have. That’s all for now, and I’ll see you in the next video.

109 comments
GBuckne
GBuckne

At first I didn't see it, but finally noticed a darker and lighter line about 1/32 of an inch.

linux vps
linux vps

What a material of un-ambiguity and preserveness of valuable familiarity on the topic of unexpected feelings.|

Michael McPartlin
Michael McPartlin

Videos are great. The voice is very easy to listen to and the content is correct. Unfortunately, I am unable to see the gradient in color once the black and grey box meet. I am unsure of whether or not my monitor is bad or my eyes are bad. Either way, thanks for the content.

Hordkorowiec328
Hordkorowiec328

Could someone give a link to that community forums? I couldn't find it on IB site :-/. And I am too a bit confused. Inhibition coming out from more stimulated cells (light color) would result in dark color being perceived as even darker near the edge. I, however, see area around the black figure as somewhat lighter so there has to be extra stimulation going on. However, I guess that the point of the video was to give a general idea how it works (Ie, that it happens in retina - not in brain)

WhimsicalEccentrics
WhimsicalEccentrics

Thank You! You cleared up what I spent hours trying to figure out in under five minutes!

SuperMonster62
SuperMonster62

And I can even see the lighter area on my phone lol

soska doll
soska doll

very helpful ! thaaaaaaaaaaaanks :)

soska doll
soska doll

... very helpful thaaaaaaaaaanks

karismamac
karismamac

This was very helpful! Especially the visual aid! Understand it a whole lot better now! XD Thanks!

slothobsessed
slothobsessed

is there a video on population coding? or maybe are you able to quickly just explain it? Cheers

slashmasteryo
slashmasteryo

Nice Video, your stuff is helping me while learning for my german oral exam tomorrow. Thanks!

ilikephilipp
ilikephilipp

Comment was too long. Read my comment entitled "Not necessarily" first, then the "It doesn't..." one. Best of luck to you!

ilikephilipp
ilikephilipp

It doesn't even look like a lighter border -- the definition is very faint, and my brain is overriding it by telling me that it is just the two rectangles. This might be the case with you, as well. The border IS very fine -- more of a shimmering at the edge, than a real color difference -- it's just a minor detail, one of those blink-it-and-you'll-miss-it, kind of things.

ilikephilipp
ilikephilipp

Not necessarily. I couldn't see it at all, at first. The two rectangles are diffferent colors (you do see that part, right?). One is grey (on the right), the other is dark grey (to me, it looks black). When Leslie brought the two rectangles in contact, the thing I can see clearly is that they are, in fact, different colors. One is darker, (left one), one is lighter (right one). The thin strip Leslie is talking about is very small, and's at the very edge of the border between the two rectangles.

kboci88
kboci88

5 hours of reading and messing up concepts got clear in 5 minutes!thx!

kboci88
kboci88

5 hours of reading and messing up concepts got clear in 5 minutes!thx!

kboci88
kboci88

5 hours of reading and messing up concepts got clear in 5 minutes!thx!

shoutatthesky
shoutatthesky

I don't see it either. When I first heard about lateral inhibition I was blown away. This video does not describe it well. I don't think there is anything wrong with your eyes just this person's description of the concept.

shoutatthesky
shoutatthesky

I don't see it either. When I first heard about lateral inhibition I was blown away. This video does not describe it well. I don't think there is anything wrong with your eyes just this person's description of the concept.

Yvonne
Yvonne

Thank you so much for posting the video's on the Special Senses! We have a test on Tuesday and your video's always make things clear to me.

bigdaddykenkuo
bigdaddykenkuo

This video is incredibly resourceful. I'm using this to study for my Behavioral Neuroscience Exam. Thank you, and I like your accent.

bigdaddykenkuo
bigdaddykenkuo

This video is incredibly resourceful. I'm using this to study for my Behavioral Neuroscience Exam. Thank you, and I like your accent.

InteractiveBiology
InteractiveBiology

Unfortunately, Leslie has a lot of work to do right now to be able to attend to the number of emails he's been receiving lately. I would strongly suggest though that you go and see an eye doctor about your observations just to be sure. We hope it's nothing that complicated... Do take care!

pfshepherd2010
pfshepherd2010

Is it bad if I don't see the lighter edge when you combine the two shades of gray? I am using a 1080p, 120hz, 22inch computer monitor and full screen 720p hd video stream. I don't see it. I have looked at other pictures and videos that demonstrate this concept and I still don't see but my friend does. What does this mean about my eyes? Am I going color blind?

InteractiveBiology
InteractiveBiology

@pfshepherd2010 Unfortunately, Leslie has a lot of work to do right now to be able to attend to the number of emails he's been receiving lately. I would strongly suggest though that you go and see an eye doctor about your observations just to be sure. We hope it's nothing that complicated... Do take care!

InteractiveBiology
InteractiveBiology

@pfshepherd2010 Unfortunately, Leslie has a lot of work to do right now to be able to attend to the number of emails he's been receiving lately. I would strongly suggest though that you go and see an eye doctor about your observations just to be sure. We hope it's nothing that complicated... Do take care!

InteractiveBiology
InteractiveBiology

Unfortunately, Leslie has a lot of work to do right now to be able to attend to the number of emails he's been receiving lately. I would strongly suggest though that you go and see an eye doctor about your observations just to be sure. We hope it's nothing that complicated... Do take care!

pfshepherd2010
pfshepherd2010

Is it bad if I don't see the lighter edge when you combine the two shades of gray? I am using a 1080p, 120hz, 22inch computer monitor and full screen 720p hd video stream. I don't see it. I have looked at other pictures and videos that demonstrate this concept and I still don't see but my friend does. What does this mean about my eyes? Am I going color blind?

pfshepherd2010
pfshepherd2010

Is it bad if I don't see the lighter edge when you combine the two shades of gray? I am using a 1080p, 120hz, 22inch computer monitor and full screen 720p hd video stream. I don't see it. I have looked at other pictures and videos that demonstrate this concept and I still don't see but my friend does. What does this mean about my eyes? Am I going color blind?

pfshepherd2010
pfshepherd2010

Is it bad if I don't see the lighter edge when you combine the two shades of gray? I am using a 1080p, 120hz, 22inch computer monitor and full screen 720p hd video stream. I don't see it. I have looked at other pictures and videos that demonstrate this concept and I still don't see but my friend does. What does this mean about my eyes? Am I going color blind?

InteractiveBiology
InteractiveBiology

All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions. All the best

zusamin1
zusamin1

lighter becomes lighter. darker becomes darker. darker side gets more inhibted as it is less stimulated than the lighter side. But why the edge on darker side looks even darker? more inhibition reached to the edge than the far end? Lighter side looks lighter in the edge why? are there inhibition to the non-edge side of the lighter side? why? Is there selective inhibition to cons and rods? im so confused :s

InteractiveBiology
InteractiveBiology

@zusamin1 All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions.

All the best

InteractiveBiology
InteractiveBiology

@zusamin1 All questions are answered in the Interactive Biology community forums from now on. Go to the website in the description and then visit the community. This is to make it as efficient as possible as we have multiple people over there to help answer questions. All the best

zusamin1
zusamin1

lighter becomes lighter. darker becomes darker. darker side gets more inhibted as it is less stimulated than the lighter side.
But why the edge on darker side looks even darker? more inhibition reached to the edge than the far end?
Lighter side looks lighter in the edge why? are there inhibition to the non-edge side of the lighter side? why?
Is there selective inhibition to cons and rods?
im so confused :s

zusamin1
zusamin1

lighter becomes lighter. darker becomes darker. darker side gets more inhibted as it is less stimulated than the lighter side. But why the edge on darker side looks even darker? more inhibition reached to the edge than the far end? Lighter side looks lighter in the edge why? are there inhibition to the non-edge side of the lighter side? why? Is there selective inhibition to cons and rods? im so confused :s

Bpatel8519
Bpatel8519

You are excellent. This helped me out so much for my Physiological Psychology exam. Thanks!

InteractiveBiology
InteractiveBiology

@Bpatel8519 Great to hear. Thanks for the feedback. Stay tuned for more!

InteractiveBiology
InteractiveBiology

@Bpatel8519 Great to hear. Thanks for the feedback. Stay tuned for more!

Bpatel8519
Bpatel8519

You are excellent. This helped me out so much for my Physiological Psychology exam. Thanks!

Bpatel8519
Bpatel8519

You are excellent. This helped me out so much for my Physiological Psychology exam. Thanks!

Bpatel8519
Bpatel8519

You are excellent. This helped me out so much for my Physiological Psychology exam. Thanks!

Bpatel8519
Bpatel8519

You are excellent. This helped me out so much for my Physiological Psychology exam. Thanks!